Is truss a type of beam bridge?

It's a late nineteenth century Bascule - twin leaf at that. It is a sort of prefabricated Suspension bridge with the bascule machinery in the towers for the two folding leaves.

This is a description of Tower Bridge - not London Bridge.

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It's also not a suspension bridge. A suspension bridge has a deck suspended from cables, and cannot be opened. The rest of the technical description is correct.